Taiwanese Patent No. 163856 discloses a conventional brake caliper device adapted to be mounted to a vehicle body and adapted to be used with a brake disk. The conventional brake caliper device includes a positioning frame that is adapted to be fixed to the vehicle body and that has opposite side parts for flanking the brake disk, a brake caliper that has opposite portions for flanking the positioning frame and the brake disk, and first and second brake pads that are respectively disposed at opposite sides of the brake disk. The positioning frame includes two guiding members. The brake caliper includes a first seat that is slidable relative to the positioning frame along an axis parallel to a central axis of the brake disc, and a second seat that is connected to the first seat. The first seat is formed with two receiving holes that respectively receive the guiding members, and a pressure member for pushing the first brake pad to abut against the brake disk. The second seat is proximate to the second brake pad. When the pressure member pushes the first brake pad to abut against the brake disk, the brake caliper is driven by a counterforce to move oppositely such that the second brake pad is simultaneously driven to abut against the brake disk.
However, since the guiding members of the positioning frame extend through an upper portion of the first seat, the positioning frame is easily driven by its own weight and the weights of the first and second brake pads to become inclined, such that the braking process become less smooth or even nonfunctional, which can be proven fatal.